The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A vehicle that includes an internal combustion engine may produce exhaust with varying concentrations of oxygen. The vehicle may include one or more oxygen sensors to monitor the oxygen concentration in the exhaust. Oxygen sensors typically include a sensor element and a heating element. The sensor element operates effectively after reaching a predetermined sensor temperature (e.g., 600° C.). An engine control module may actuate the heating element to heat the sensor element to the predetermined sensor temperature.
The engine control module determines that the heating element is at the predetermined sensor temperature based on a resistance of the heating element and a heating element model. The engine control module determines the resistance of the heating element based on voltage applied to the heating element and current through the heating element. The heating element model provides a temperature of the heating element based on the resistance of the heating element.
The resistance of the heating element varies among oxygen sensors. The heating element model of each oxygen sensor therefore should be determined when the oxygen sensor is installed in the vehicle. Typically, the heating element model of a particular oxygen sensor is determined based on the resistance of the heating element after a cold start, when the vehicle is at ambient temperature (e.g., 20° C.).